mir-54/55/56::gfp was detected in the cell nuclei of essentially all somatic cells when driven by a region extending 6.0 kb upstream from the
mir-54 coding sequence. Expression was first observed in the 28-cell stage embryo, weakly and diffusely within nuclei of all somatic cells. The expression then became strong from 200-cell stage onward and persisted throughout embryogenesis, larval stages and adulthood.